Preparation of 1,2-butylene oxide

ABSTRACT

A process for the preparation of 1,2-butylene oxide by the catalytic hydrogenation of vinyl oxirane, in which use is made of a palladium catalyst on a support of barium sulfate, zirconium oxide or titanium dioxide or a rhenium-containing supported palladium catalyst.

This application is a 371 PCT/EP95/02337 , Jun. 16, 1995.

The present invention relates to a process for the preparation of1,2-butylene oxide by the catalytic hydrogenation of vinyl oxirane

The catalytic hydrogenation of vinyl oxirane over catalysts consistingof palladium on aluminum oxide or palladium on activated charcoal isdescribed in U.S. Pat. No. 5,077,418 and U.S. Pat. No. 5,117,013 andalso in Neftekhimiya 33, 131 (1993). The yields, selectivities andconversions in this process are unsatisfactory.

It was the object of the present invention to provide a process for thepreparation of 1,2-butylene oxide, which makes it possible to prepare1,2-butylene oxide from vinyloxirane with better conversions, yields,and selectivities than in the prior art.

Accordingly, we have found a process for the preparation of 1,2-butyleneoxide by the catalytic hydrogenation of vinyl oxirane, wherein use ismade of a palladium catalyst on a support of barium sulfate, zirconiumdioxide or titanium dioxide or a rhenium-containing supported palladiumcatalyst.

When carrying out the process of the invention, the vinyl oxirane orsolutions of vinyl oxirane are hydrogenated in a solvent which is inertunder the reaction conditions in the presence of the catalysts to beused in the invention at temperatures generally of from -10° to 100° C.,preferably from -5° to 50° C. and more preferably from 0° to 30° C.under a pressure of from 1 to 100 bar, preferably from 1 to 50 bar, inparticular from 1 to 30 bar.

The process of the invention can be carried out without the use ofsolvents or, advantageously, in the presence of a solvent inert underthe reaction conditions, for example, in the presence of alcohols, suchas methanol, ethanol, propanol, isopropanol, n-butanol, isobutanol ortert-butanol, hydrocarbons, such as petroleum ether, benzene, toluene orxylene, or dipolar-aprotic solvents, such as N-alkyllactams, egN-methylpyrrolidone or N-octylpyrrolidone, or, in particular, ethers,such as tetrahydrofuran, dioxane, methyl-tert-butyl ether, di-butylether, dimethoxy ethane, diethyl ether or diisopropyl ether.

The process of the invention can be carried out either continuously orbatchwise, in the gas phase or in the liquid phase. When the process iscarried out continuously, tubular reactors or cascades of reactors canbe used for example, which can be operated in the upward-flow mode ordownward-flow mode.

Advantageously, the catalysts are arranged in these reactors in the formof a fixed bed. When the process is carried out batchwise, the catalystcan be used, eg, in stirred reactors in the form of a suspension or,advantageously, as a fixed bed, eg, when use is made of recyclereactors.

The palladium content of the catalysts which can be used in theinvention is generally from 0.1 to 5 wt %, preferably from 0.3 to 3 wt %and more preferably from 0.5 to 2 wt %, calculated as Pd and based onthe total weight of the catalyst.

The rhenium-containing supported palladium catalysts which can be usedin the invention contain rhenium in a ratio, by weight, in relation topalladium, generally of 1 to 99, preferably 10 to 90, and morepreferably 40 to 60.

Apart from the support materials which can be advantageously used forthe catalysts containing only palladium as active ingredient ie bariumsulfate, zirconium dioxide, or titanium dioxide, other supportmaterials, such as activated charcoal, silicon dioxide, silica gel, orkieselguhr can also be used to advantage.

The preparation of the palladium catalysts or the catalysts containingpalladium and rhenium can be effected in conventional manner, forexample, by impregnating the support materials with aqueous solutions ofwater-soluble compounds of palladium or of palladium and rhenium, forexample, with the nitrates, sulfates, halides, or carboxylates ofpalladium and rhenium, drying the impregnated supports, eg, attemperatures of from 50° to 200° C., preferably from 100° to 150° C.,then effecting calcination at temperatures generally of from 200° to600° C., preferably at a temperature of from 300° to 500° C., andreducing the catalyst thus obtained by treatment with reducing agents,such as hydrazine, hydrogen, or hydrogenous gases, for example, attemperatures of from 100° to 300° C., preferably at a temperature offrom 150° to 250° C. When carrying out reduction and activation of thecatalyst with hydrogen, reduction is generally continued until no moreappreciable amounts of water are formed.

The reduction and activation of the catalysts with hydrogen can takeplace in situ in the hydrogenating reactor during hydrogenation, but thecatalysts are preferably reduced and activated prior to their use in theprocess of the invention.

When use is made of thermally unstable salts of palladium and rheniumfor impregnation of the support material the activation of the catalystcan alternatively take place thermally by heating the impregnatedsupports to temperatures generally of from 100° to 700° C., andpreferably of from 200° to 600° C.

Instead of using the aforementioned palladium or rhenium salts,water-soluble palladium complex compounds or water-soluble salts of theoxyacids of rhenium, for example, alkali metal or ammonium rhenates orperrhenates and solutions of rhenium heptoxide (Re₂ O₇) can be used forimpregnation of the supports.

When preparing palladium and rhenium-containing supported catalysts, theelements rhenium and palladium can be applied to the support materialsimultaneously or successively for impregnation of the support material.

The purification of the reaction mixture in order to isolate1,2-butylene oxide can take place in conventional manner, eg, bydistillation.

The vinyl oxirane required as starting material can be prepared, eg, bythe method described in U.S. Pat. No. 4,897,498 by partial oxidation of1,3-butadiene over silver catalysts.

1,2-butylene oxide can be used, eg, as fuel additive or as stabilizerfor chlorinated hydrocarbons.

EXAMPLES

Hydrogenation of vinyl oxirane to 1,2-butylene oxide was carried out ina stirred autoclave having a capacity of 50 mL. In each case, thereactor was charged with 0.1 g of the respective catalyst and 2.5 g ofvinyl oxirane in 22.5 g of tetrahydrofuran.

The hydrogenating conditions temperature, pressure, and residence timeand the degree of hydrogenation obtained (determined by calibrated gaschromatography of the hydrogenated effluent) are listed in the table.

                                      TABLE                                       __________________________________________________________________________                Hydrogenation                                                                            Residence                                                          Temperature                                                                          Pressure                                                                          Time Conversion                                                                          Yield  %!                                   Catalyst*    °C.!                                                                          bar!                                                                              h!   %!   1,2-B                                                                            BA n-BuOH                                __________________________________________________________________________    0.5% Pd/BaSO.sub.4                                                                        20     20   9   100   67 14 11                                    1% Pd/BaSO.sub.4                                                                           0      4  15   100   82 4  6                                     1% Pd/BaSO.sub.4                                                                           0     20  12   100   81 5  2                                     1.5% Pd/BaSO.sub.4                                                                        20      4  15   100   70 17 10                                    1% Pd/ZrO.sub.2                                                                           20      8  15   100   60 20 14                                    3% Pd + 3% Re/C                                                                            0     20  11   100   75 6  9                                     0.5% Pd + 0.5% Re/Al.sub.2 O.sub.3                                                        50     40   8   100   71 9  8                                     __________________________________________________________________________     *Percentages by weight, based on total catalyst                               1,2B: 1,2butylene oxide                                                       BA: nbutyraldehyde                                                            nBuOH: nbutanol                                                          

We claim:
 1. A process for the preparation of 1,2-butylene oxide by thecatalytic hydrogenation of vinyl oxirane, wherein a palladium catalyston a support of barium sulfate, zirconium dioxide or titanium dioxide ora rhenium-containing supported palladium catalyst is used.
 2. A processas defined in claim 1, wherein use is made of a palladium catalysthaving a palladium content of from 0.1 to 5 wt %.
 3. A process asdefined in claim 1, wherein use is made of a palladium catalyst having apalladium content of from 0.3 to 3 wt %.
 4. A process as defined inclaim 1, wherein the hydrogenation is carried out at a temperature offrom -10° to 100° C. and under a pressure of from 1 to 100 bar.
 5. Aprocess as defined in claim 1, wherein the hydrogenation is carried outin a solvent.
 6. A process as defined in claim 1, wherein thehydrogenation is carried out in a dipolar-aprotic solvent.